Apparatus for the separation of solid substances differing in specific gravity



NOV. 25, 1%52 EM 2,619,229

APPARATUS FOR THE SEPARATION OF SOLID SUBSTANCES DIFFERIWG IN SPECIFIC GRAVITY Filed Jan. 18, 1949 INVENTOR.

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Patented Nov. 25, 1952 APPARATUS FOR THE SEPARATION OF Y SOLID SUBSTANCES SPECIFIC GRAVITY DIFFERING IN Jan N. J. Leeman, Hoensbroek, Netherlands, as-

signor to Maatschappij voor Kolenbewerking Stamicarbon N. V., Heerlen, Netherlands Application January 18, 1949, Serial No. 71,452 In the Netherlands January 26, 1948 2 Claims.

This invention relates to an apparatus for the separation of mixtures of solid substances differing in specific gravity.

The separation of mixtures of solid substances difiering in specific gravity, e. g. coal and shales, according to the float and sink method with the aid of a suspension or a heavy fiuid usually takes place in a washing tank provided with an endless Scrapper-chain which travels both along the surface and along the bottom of the bath, thus removing the separated products in opposite direction. A similar device has e. g. been described in the Dutch Patent Specification No. 55,781.

This construction naturally implies that the substance to be treated must be supplied to the bath through the spaces between the plates or by shoving into the bath by means of the scraper chain. The latter method is less desirable as it has been found, that in order to effect a good separation, the mass must have a certain velocity when being supplied to the bath; for this reason the mass has to be dropped. According to the drawing referring to said patent specification this is attained by causing the scraper chain to dive into the bath to a certain depth at the point where it enters the liquid, after which it rises again and reaches the surface at a certain distance from the point of immersion and travels along the surface of the bath. Since in this case the mass introduced, or at least part of it, has to pass through the openings between the plates it often occurs that part of the mass is caught and carried off by said plates which are usually toothed and provided with projections, hence a good separation is impossible.

According to the present invention this drawback is eliminated while yet the requirement is met that the mass to be separated shall be plunged into the bath. According to the invention this is attained by causing an upper run of the scraper or conveyor, moving towards the bath, to carry the mass to be separated, which gradually passes from between the plates and is released before the chain reaches the bath so that the particles fall into the bath at a certain velocity. The device according to the invention differs from the washing tank described in the Dutch Patent Specification 55,781 in that the scraper chain, which in the latter case dives into the bath at the highest inclination possible and subsequently rises till it reaches the surface again at a certain distance from the point of immersion, is now elevated over the first section of the bath. By the present invention, the conveyor is guided in such a way that it passes in an elevated position over said first section of the bath and subsequently travels along the surface of the bath. This may be carried out advantageously if an upper run of the chain is passed into the bath along a slanting plate from which it diverges or moves away gradually. The mass to be separated is carried downwards along the plate by the scraper chain or conveyor and the particles of the mass are released from the conveyor at various points in the downward travel of the upper run as hereinafter described and plunge into the bath. The plate may end at a certain distance from the bath.

Because the above-mentioned upper run of the conveyor or scraper chain gradually diverges from the plate, a further advantage may be gained, provided the plate is properly adjusted.- In more detail, the space between this run of the conveyor and the plate gradually increases toward the bath so that the material retained by the conveyor may fall into the bath at various points depending upon how the size of the particles compares with the width of the space. In other words at least some of the small particles are released from the conveyor first whereas the bigger lumps are only released at a lower level. Consequently the latter will not acquire such a high velocity that they will shoot through in the bath and be caught by the chain run moving along the bottom of the tank and before a separation according to specific gravity has taken place, neither will the smaller particles plunge into the bath at too small a velocity, and, as a result, not be wetted. Non-wetting can result if the mass is carried into the bath by the scraper chain. Also, with insufficient wetting, the particles of a higher specific gravity may not sink but will be carried off together with the specifically light particles. The required adjustment of the plate naturally depends on the composition of the material to be treated.

The invention will be explained with the help of the drawing in which by way of example a device according to the invention for the separation of coal and shales with the aid of a heavy fluid or a suspension has been represented. In the trough shaped washing tank 1, filled with a heavy fluid or a suspension, the endless scraperchain 2 including transverse elements to form compartments moves over the driving shafts 5 and 6. The portion of the chain moving along the surface in run 3, carries oif the light particles, whereas the particles which sink are caught by the run 4 and transported along the bottom of the tank I. From the driving shaft 5 the chain passes along plate I from which it downwardly diverges. The conveyor belt 8 supplies the material to be separated to the scraper chain at 9 by which it is carried further downwards. The released coaland shale particles plunge into the bath where they are properly brought in contact with the fluid and have the opportunity of separating into two fractions. Both as a result of the plunging feed and of the movement of the scraper chain in the washing tank a current is evolved directed towards the right in the drawing so that particles are urged in that direction Where the floating part, the coal, is caught by the chain emerging from the bath and carried along sieve la. The sunken particles are carried upwardly at the left by the chain and passed along the perforated part I3 of the wall of the washing tank.

The coal is discharged through the orifice H and the shale is discharged through the orifice I2.

Naturally the invention is not restricted to the separation of coal and shale nor to the device described in the example given but may also be used for the separation of other mixtures of solid substances and in devices used for the purpose to which the above described principle is applicable.

I claim:

1. Apparatus for sink and float separation of solid materials differing in specific gravity and grain size, comprising a tank for a separating medium, an element including an upwardly facing surface above the level of the bath and which is inclined with respect to the vertical at such angle as to permit material to move down said surface by gravity, a conveyor including a run movable downwardly in a plane intersecting the upwardly facing surface of said element at the 4 upper end and which plane is spaced from said surface of said element at the lower end, said conveyor including transverse elements spaced lengthwise thereof to form material receiving compartments opening toward said surface during movement in said run, the angle of divergence between said run and said surface, and the angle of said run with respect to the vertical, being sufficient to enable material of small grain size to fall free of the conveyor and into the bath at the beginning of the run and material of increasingly larger grain size to fall free of the conveyor and into the bath during the movement downwardly in the run.

2. Apparatus of the character described in claim 1 wherein said conveyor is endless and includes horizontal runs respectively positioned at the surface portion and adjacent the bottom of the tank, said horizontal runs being movable in opposite directions to respectively remove light and heavy materials from said tank.

JAN N. J. LEEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 854,987 Dunning May 28, 1907 994,654 Parker June 6, 1911 1,290,515 Conklin Jan. 7, 1919 1,643,596 Zuckerman Sept. 27, 192'? 1,839,117 Nagelvoort Dec. 29, 1931 FOREIGN PATENTS Number Country Date 528,914 Great Britain Nov. 11, 1940 

